This invention relates to an oil type damper which relies on the viscosity of oil to brake the opening or closing motion of, for example, a lid in some type of machine.
In a cassette tape recorder or a video tape recorder, for example, there is used a damper for braking the sudden release motion of the lid of a cassette tape holder during the opening or closing of the tape holder for the purpose of abating impacts generated during the release motion.
The damper of this kind generally comprises a base adapted to be secured on the body of a given machine and a rotor accommodated rotatably within the base and adapted to receive the rotational opening or closing motion of a lid of a cassette holder, for instance. The methods for applying a braking action on the rotation of the rotor relative to the base are broadly divided into the frictional contact method and the method making use of the viscosity of an oil such as silicone oil. Of these two types, the oil type proves more desirable in terms of durability of the damper and the sensation perceived by the user during the operation of the damper.
Generally, the oil type damper comprises a cylindrical base, a rotor accommodated in the cylindrical base, and a number of other parts including a cap and a toothed wheel connected to the rotor. The fact that the number of component parts is large implies that the oil type damper is expensive. Moreover, the oil type damper is quite bulky and requires considerable time and labor to assemble. There is also a possibility that because of mismatching between component parts, the completed oil type damper will have unwanted play and consequently suffer from poor operational precision.